Traffic information and guidance systems are more and more important tools to be able to cope with traffic conditions in cities and on densely trafficked highways.
In prior art it is known how to utilize Global Positioning System (GPS) transceivers in navigation terminals installed in cars, and how pedestrians can find destinations when walking and being guided by for example apps from Google Map installed in Smartphones being equipped with GPS transceivers.
Such solutions are usually of great help, but there may be incidents for example which can block or which require changes of a selected route after a navigation terminal for example has calculated an optimal route to follow. Further, if many road users are travelling at the same time, for example to a major sport event, the optimal route found by a navigation tool may no longer be an optimal route. This scenario illustrates an important aspect of road guidance systems since an optimal route in the sense of being objectively the shortest route between two geographical locations may not subjectively be viewed or be experienced as an optimal route by all road users. The time of travel between two points are of course important, but there might also exist road user preferences like a personal perception about what is the best route to follow, or a road user wants to pass a certain point of interest like a viewpoint, or a restaurant etc. Therefore, it is necessary with a more complex measure of an optimal route like a metric that takes into account both objective measurable traffic conditions as well as subjective user preferences having an impact on a specific traffic advice or guidance.
There exist prior art mathematical theories that can model some typical examples of user behaviour in traffic and the impact on road conditions. For example, it is common to look at game theory and one important concept is the concept of Nash equilibrium. A simple way of explaining the concept of the Nash equilibrium related to traffic is by a simple example of two road users. Road user A and road user B are in Nash equilibrium if road user A is making the best decision for a travel route by taking into account road user B's decision for his travel route, and road user B is making the best decision he can by taking into account road user A's decision. Likewise, a group of road users are in Nash equilibrium if each one is making the best decision about the traffic that he or she can do by taking into account the decisions of the others in the traffic.
Another interesting aspect of road conditions and improvement of traffic flow is the availability of road capacity between a starting point and a destination point. One could believe that the traffic flow with respect to travel time between these points would improve if the road capacity increases. However, a German mathematician Dietrich Braess found what is denoted the Braess paradox. The paradox states that adding extra capacity to a network when moving entities selfishly choose their own routes in the network may reduce overall performance. This is because the Nash equilibrium of such a system is not necessarily optimal. Selfish behaviour does not favour cooperation between road users in the traffic.
For example, in Seoul in South Korea an increase in traffic flow capacity around the city were found when removing an existing motorway segment. In Stuttgart in Germany, in 1969, a new road network did not provide the expected improvement in travel time before closing a new section of the road for traffic. The same phenomena occurred in New York City in 1990 when traffic in the 42nd street was blocked. This reduced the traffic congestion in the area.
Traffic flow problems are phenomena that interests mathematicians and development of many theories and empirical models trying to make traffic forecasts about traffic conditions are popular in the mathematical community.
Frank Knight did some of the first attempts to produce a mathematical theory with respect to traffic flow in the 1920s. The attempts provided a theory of traffic equilibrium, which was refined into Wardrop's first and second principles of equilibrium in 1952.
Even with the significant computer processing power that exists today there has been no substantial results from systems applied to real traffic flow conditions. Current traffic models uses a mixture of empirical and theoretical techniques. These models are then making traffic forecasts and the forecasts tries to identify areas of congestion where the current traffic on roads needs rerouting.
Therefore, not just only physical conditions provide basis for proper guidance in traffic. A combination of physical available capacity and user behaviour and preferences with respect to utilizing available capacity of road systems is the foundations for proper advices and guidance in the traffic.
The psychological aspect of road user behaviour is best illustrated by the simple fact that most road users that need to make a deviation from an intended route due to traffic congestion for example, will choose what appears to be the best alternative route around the problem. When everyone makes the same alternative route, which usually is an obvious choice, this route will probably soon experience congestion also. When applying a navigation tool to find an alternative route, the algorithm will probably also propose the same route to everyone using the same navigation system or algorithm.
Accidents or incidents are happening at random and prediction in advance is impossible, which is adding complexity to the problem. Further, the impact on traffic flow due to an accident or incident is not always evident. Road traffic passing a location of a road accident will of course be influenced by the accident, for example just by the fact that it is human to slow down the speed and look at what has happened. If the traffic slows down and the traffic density is high, the lower speed condition may start to propagate throughout a larger and larger area. Therefore, an accident or incident is seldom a stationary phenomenon limited to a certain geographical area, but is a situation that can have a growing impact on traffic conditions over time, but being limited within a specific geographical area, and/or affect a larger part of the geographical area over time. Reversal of the situation will usually happen when for example emergency agencies starts to clean up after an accident or incident. First, the size of the affected area may start to decrease, and over time the traffic conditions in the area of the accident will return to the traffic situation before the accident. Therefore, a road accident or incidents in the traffic will be associated with an impact factor magnitude reflecting seriousness of a traffic incident or event, and an impact area size around the accident or incident that respectively are functions of time.
Even planned road works may appear to road users as an unexpected incident because it may happen they missed a notice informing about the work in progress in the news, or have overlooked an information display detailing the road work before they arrived at an area affected by the road work. It could also be that a signpost has not yet been put in place.
From a road user's perspective, the road user may activate a navigation terminal and enter a planned destination. The system then calculates a route to follow, and if there is an accident or incident that will influence the traffic conditions somewhere along the calculated route, a traffic server may online notify the navigation tool, and the navigation system can provide an alternative route online even when travelling.
The time dependency of the impact factor magnitude and impact area size can make the proposals of alternative routes made by the navigation system discussed above obsolete. During the time span from the notification of the accident or incident from a traffic server until a road user approaches the impact area, the impact area size can for example grow. Dependent on current position of the car, there might no longer exist any alternative route out of the area since the time dependent evolution of the accident or incident now locks (due to emerging queues blocking junctions for example) the possible alternative routes out of the area.
Therefore, besides time dependent impact factor magnitude and time dependent impact area size, there will also be a time and distance dependent point of a specific location relative to for example an incident or event where a road user can or should be notified about the traffic problems ahead of him. According to an aspect of the present invention, such a location should serve as a decision point for the road user, wherein the road user can receive guidance and where the road user can decide about his further travelling. The road user may also receive an advice from a traffic server monitoring traffic conditions, for example about alternative roads. Before a road user passes a location of a decision point there are available alternative routes around the specific traffic problem by definition. If no available alternative routes were available after passing the decision point there would be nothing to decide, hence not a decision point.
Due to the dynamic behaviour of an impact factor magnitude and an impact area size, the relevance of traffic messages related to an incident or event may be short lived. Therefore, a traffic server system intending to provide correct traffic information and/or advice to road users can only rely on up to date information. However, the question remains when a traffic server can submit which specific up to date information to which road user. On one hand, a traffic server may acquire traffic information from police, fire brigades, from TV stations monitoring traffic from helicopters etc. On the other hand, only the road user knows which specific routes the road user will follow, and therefore only the road user can decide which specific traffic information and guidance a traffic server can provide for him. If the road user request such information too early, the information may be obsolete when arriving at a destination linked to a traffic problem. If the road user requests the information too late, the traffic conditions may trap the road user. Therefore, there is a contradiction between the requirements of the traffic server and the road users. In a sense, there is no correlation between them with respect to their own actions, their knowledge and current geographical positions and needs.
The decision point location relative to a location of an accident or incident depends for example on topological factors, i.e. how many side roads exist between a current position of a car and the location of an accident or incident. This dependency may also be dependent on direction of approach towards an accident or incident. For example, if an accident happens at the outskirt of a town there will probably be more alternative roads available if one comes from the city centre compared with coming from the countryside outside the city perimeter. Further, traffic regulations like one-way roads etc. may also influence the number of available alternative routes around an impact area. Therefore, the decision point location relative to the location of an accident or incident may be located at a completely different distance than the perimeter of the impact area as such. The main parameter deciding a location of a decision point is that there must be available side roads with acceptable traffic conditions between the location of a decision point and a traffic incident or traffic event. However, in view of the dynamic behaviour of the impact magnitude and impact area size the location of a decision point is also dynamically changed and correlated with the time dependent evolution of the impact area magnitude and impact area size.
There is also another time dependent problem related to updates of information in traffic servers. For example, authorities like the police, fire brigade, hospitals, road authorities etc. can report accidents. When a car accident happens someone is calling an emergency number and police, ambulance etc. is arriving at the location of an accident. When a police car for example is arriving, an experienced police officer can assess the degree of seriousness of the accident, i.e. impact factor magnitude. However, the time between an accident and the reporting and eventual update of a navigation map for example about the incident will take some time. Even during 10 minutes delay, several hundred cars may be jammed creating a queue that may block side roads as well. The consequence will start to grow both in impact magnitude and impact area size. One interesting aspect of the phenomena is that trapped people in a queue do not know or understand always why there is a queue. Indeed, it is very seldom a need of informing about why there is a traffic problem. The only valid information that is of interest is traffic problems head of you when continuing travelling in the current direction. This is relevant information. The next valid action of a system is then to tell you how to drive to avoid possible problems ahead of you.
Even when notifying a traffic server about an incident quickly, there is no incentive among police officers, first aid personal etc. to update the traffic server with progress information since they are probably busy with the incident itself, i.e. doing their work. Maybe update of status of the incident will happen when the situation or incident is over, or when they submit their report about the situation to their own organisation. During this time, the impact area may grow or other incidents in a same area may worsen the situation without reporting the other incidents.
Therefore, bad road conditions provoked by a local incident can grow in impact area size, and in the periphery of this impact area there will probably be new incidents due to a queue for example that no one at the scene knows originally was provoked by the local incident. Therefore, linking information and guidance around incidents in the periphery of an impact area to an evolution of the original local incident that provoked the problem is not necessary. A queue like this can continue to exist for a long time after the original incident that provoked the queue is over as known in the prior art. This should be reflected in the information and guidance provided to road users around incident points in the periphery of an impact area.
The server may have a system assessing road conditions based on accident and/or incidents. However, the quality of any advice or guidance being the result of the assessment is dependent on the current situation or impact of any accident or incident. Any road user needs advice and alternatives related to the point in time the road user actually asks for an advice. Therefore, it is a road user's geographical position and point in time of arrival to a geographical position that should activate updates of information and analysis, calculations of traffic flow algorithms etc. related to an area around the geographical position of the road user. Linking the information and guidance to a forecast of coming road conditions in the near future relative to the current position in time and location, and direction of travel, and/or due to the road user's selection of destination etc. is preferable.
Besides the time dependencies discussed above, also another factor can make decisions by for example a navigation terminal obsolete. This is changing road user behaviour. Even if a road user has entered a destination into a navigation terminal, the road user can decide at any time to deviate from the calculated route. He can suddenly decide to depart from the route to visit a friend, or he receives a phone call that makes it necessary to cancel the trip but does not delete the selected destination from the navigation tool. Further, road users do not have to enter a destination every time a car is used. If a road user is travelling to his workplace from home (or from the workplace to his home), he will probably not use a navigation tool at all. If an accident or incident blocks or slows down his travel to the workplace (or home) the road user will probably know many alternative routes himself, but the question that is remaining is if his choices are valid choices with respect to traffic flow conditions. The road user would still need information and guidance to qualify if a specific choice he knows or want to use is an open route to his workplace (or home), or that has an acceptable traffic flow density or not.
Therefore, a proper traffic information and guidance system rely on gathering static and nonstatic information about traffic conditions. The system must measure time dependent developments of accidents etc. with respect to impact on traffic flow and size of an impact area. The system must also be able to base guidance about road conditions to specific road users on a rather complex metric that is changing with time and location, and user behaviour of road users defining and qualifying what is an optimal route from a specific geographical location to another specific geographical location. Such guidance should be available even if a traffic information and guidance server system do not know an identity of a road user, and even when not knowing the intended destination of travel of a specific road user. When such a specific road user is in need of an advice or guidance on a specific location, the traffic and guidance server system must provide targeted and relevant information to a road user that in principle can be unknown to the system.
In prior art it is known how a computer server system may have models of maps of road systems, and a traffic server can monitor GPS positions received from GPS transceivers located in cars, or via mobile phones equipped with GPS transceivers and which are carried by road users. Then it is possible to track road user positions on modelled maps, and recording information about accidents or incidents, and the server may issue warnings to approaching road users approaching such locations. However, as discussed above, the warning may not be relevant to the road user since the road user had in mind to turn off the road that would be problematic for the travel anyhow. The new road followed by the road user may have an entirely different traffic problem that still could be a real hindrance for the continued travel. For example, a truck may have capsized and the truck and goods are blocking the road completely. Therefore, the problem is how to warn road users when one really do not know the expected behaviour of the road user. Therefore, broadcast of accidents or incidents to road users even inside a limited geographical area may not provide a solution to traffic flow problems in the area. It is important to bear in mind that when a broadcast warning is received it is most probable that most road users selects another route that is the obvious choice among the alternatives, i.e. is a main road around the problematic area etc. Then it is probable that traffic congestion can build up on the road that is the obvious choice to avoid the initial incident. Road users that do not cooperate will create problems for each other. Therefore, individual guidance from a server may also enable the server to distribute traffic load on several roads and thereby mitigate problems arising from a same advice to everyone. Further, it is rather obvious that broadcasting an advice or information makes it impossible to reach a Nash equilibrium, for example.
Further, in the example above the road user must interpret broadcasted warnings and make an assessment if a warning is relevant for the intended continued travel. In reality, this will be a task of every road user within an area. Road users must think about all the parameters discussed above when evaluating the impact of an incident or accident on selectable routes of an intended continued travel.
In prior art it is a growing trend in the auto industry to equip cars with wireless Internet facilities. In this manner there is a growing availability of a technical infrastructure that is standardized (and not proprietary), and which is common knowledge among most road users. Therefore, informing road users about traffic conditions, and even providing intelligent guidance from for example authorities over the Internet connected to wireless terminals can therefore mitigate problematic road conditions like queues etc. Tuning and operating traffic lights may speed up traffic flow in cities during rush hours. Information about respective road conditions like traffic accidents or incidents can then also help road users to select other routes, and in combination with central traffic light control such problems may not turn into hour-long queues during rush hours.
A standard Internet service is a WEB page that for example can provide the information and guidance referenced above. Segmenting such pages according to geographical areas, certain parts of a city etc. is common. When driving a car it is usually difficult for the driver to operate a wireless terminal searching for information while at the same time keeping track of other road users. Therefore, accessing such WEB pages are usually beneficial before a ride starts and the information of interest is usually of a nature that is more general. The information can include information for example about ongoing roadwork, expected weather conditions like fog conditions the next coming hours, snow conditions etc., or about major accidents, fires etc. that has been reported, but which may not be reported that it is all over.
Alternatively, or as a supplement to Internet based services, vehicle-to-vehicle networks wherein the object is to communicate to others for example if a driver is pushing the brakes of his car may be used. Submitting information about road conditions, in addition to a warning of braking the car etc., submitted over the vehicle-to-vehicle networks to cars behind the braking car is possible, and then this can trigger the cars behind to slow down immediately. A vehicle-to-vehicle network can have an interface node to standard Internet services, which makes it possible to access the network between cars from external servers via Internet protocols.
It is known in prior art to use push messages when operating a traffic information and guidance server system. A push message in this context is a message sent from a traffic server to an individual road user, or a group of road users without the need for any road user to request the message. In prior art it is known to utilize a technique denoted geofence to be able to achieve an automatic broad cast messaging system that is distributing messages to mobile users crossing a virtual defined geographical perimeter around a Point Of Interest (POI). However, since anyone that is crossing the geofence usually receives the same information there is no targeting of the information with respect to specific road users. The information will probably not provide any specific relevant guidance for a specific road user, but only be of general interest to the majority of road users crossing the geofence from any side of the geofence around the POI. Again, it may be a problem, as discussed above, that a same warning or information of an accident, or incident, or a queue or any traffic related problem etc. is triggering a collective choice of selecting a same alternative route. The alternative rout may be the obvious choice to follow around problematic areas.
The example of a geofence above enables a server to identity the approximate geographical position a road user is located on, and the server can for example track or follow the movements of the road user to a next POI. This recorded movement can then qualify targeted traffic information to this specific user. However, it may be a legal issue if a traffic server can follow movements of a road user without the road user's explicit consent to do so. Further, why should a server record all movements of all cars in a city? Besides being a probable legal issue the technical challenge of tracking positions of millions of cars can be a problem, at least a technical problem if the solution needs to be scalable, which may be a necessary condition for example during rush hours. Further, broadcasting of information is an incentive to collective behaviour of road users, which probably create new traffic problems.
US 2002/0065599 A1 disclose a traffic management system (TMSYS), which comprises a road network (RDN) on a physical layer (PL) and at least a packet switched control network (PSCN) on a traffic control layer (TCL). The vehicle traffic formed on the physical layer (PL) by a plurality of vehicles (C1-Cx) travelling along a plurality of road sections (RDS1-RDSm) of the road network is mapped into a packet traffic constituted by a plurality of packets (CP1-CPx) routed along a plurality of packet routing links. Packet control units (PCU1-PCUn) of the packet switched control network (PSCN) are adapted to control the packets (CP1-CPx) on a respective packet routing link (PRL1-PRLn) in the traffic control layer (TCL) to correspond to or simulate a respective vehicle (C1-Cx) on a corresponding road section on the physical layer (PL). The traffic management system (TMSYS) thus treats each vehicle as a packet and can monitor, control or simulate the traffic on this physical layer (PL) by the packet traffic in the traffic control layer (TCL).
US 2011/0246594 A1 disclose a commuter group service (CGS) which allow commuters to join commuter groups enabling them to socialize while commuting. Through the commuter groups, the users may share commuting routes, traffic updates, road conditions, and other information. Group members may arrange car pools, short term riding arrangements, and may contact each other. The CGS may collect information about respective group member positions, e.g. GPS coordinates, enabling the CGS to calculate traffic conditions and to select location specific information for group members. The system may include an on-line service accessible through a computer or wireless networking device. The user may log into the CGS, create or modify a user profile, and join groups of their choosing. Groups may be associated with specific events or with getting to/from work. Forming commuter groups for commuters that use private vehicles and/or public transportation is possible.
US 2003/0018428 A1 disclose a vehicle information system, which includes an in-vehicle system and a centralized server system. The in-vehicle system communicates with the server system using a wireless communication link, such as over a cellular telephone system. In one version of the system, an operator specifies a destination to an in-vehicle system, which validates the destination. The in-vehicle system transmits specification of the destination to a server system at the centralized server. The server system computes a route to the destination and transmits the computed route to the in-vehicle system. The in-vehicle system guides the operator along the route. If the in-vehicle system detects that the vehicle has deviated from the planned route, it reroute a new route to the destination using an in-vehicle map database.
US US 2008/0234921 A1 disclose a navigation device helping road users when there is a traffic congestion. The device receives real time data about slow traffic flow or low average traffic speed as an indication of a congestion. The device calculates an alternative rout by taking into account historical data about speed conditions on secondary roads weighted with the current average speed in the congestion area.
The prior art publication WO 2012122448 A1 by Lorenz Riegger et al, disclose an agricultural vehicle tracking server system that configures a moving geofence (16) about the location of a vehicle (10). A moving geofence (16) may intercept a point of interest, such as another moving geofence (16), and the server will issue an alert. The particular characteristics of the moving geofence (16) is generating the geofence in accordance with a predetermined scheme. Alerts may be weather alerts, or there can be detection of a situation where two respective geofences around two vehicles are overlapping thereby indicating a possible collision hazard. However, the teaching is about predefined actions like collision detection or weather warnings. There is no targeted information and guidance to a specific road user or road users in general. Any road user crossing a geofence around a same POI gets the same information or warning.
U.S. Pat. No. 8,306,556A by Yi-Chung Chao et al, disclose a system based on real time data. A method of operating an intelligent real-time distributed traffic sampling and navigation system includes: receiving navigation information from a client (a navigation terminal), and analysing the navigation information thereby providing traffic information, and generating a travel route based on the analysis of the navigation information; and sending the travel route to a display in communication with the client.
The international patent application PCT/EP2014/051406 with the title “A traffic surveillance and guidance system” by the same inventor as the present invention, disclose a traffic information and guidance system providing a communication channel between road users driving their respective cars. Each driver has a field of view and the basic concept is that it is possible to combine the field of views of a plurality of road users, or just between two drivers driving for example on a same road. FIG. 1 illustrates schematically a combined field or union of fields of view between a road user in car A with a field of view 1, field of view 2 of a road user in car B and a field of view 3 of a road user in car C. In this manner road users can share information that one road user can view visually while other road users may have problems with visual contact of the situation, for example because of a hilltop, a house, trees etc. Some of the technical features of the invention enabling this concept are that each road user registers himself as a member and user of a server system providing for example traffic information services. When registering, a road user selects a specific geometrical shape and size representing a model of his intended field of view, for example a circle of 500 meters diameter (or any other shape and/or dimension). The traffic server tracks geographical positions using the Global Positioning System (GPS) coordinates of cars or of mobile terminals associated with the registered road users. One important aspect of this method is the relative movement among the road users, which are establishing the union and the communication, as well as closing the communication among them when they move apart. Then the road users in a union are all relevant for each other enabling them to communicate information from the same geographical area. This invention helps and promotes road users to cooperate when for example one member of a union spots an incident and sends a message about the incident within the union. Then it is possible to achieve Nash equilibrium locally for the members of the union. In addition, the traffic server may intervene and provide specific advices to the members of the union. If not dissolving a union when road users travel away from each other, achieving Nash equilibrium can never be possible among these road users since the messages starts to be invalid information for the road users still traveling within the relevant geographical area when they receive information from members moving further and further away. This scenario is common among commuter group systems, which often allows people to stay in contact regardless of relative position between commuter members.
Even though the teaching of PCT/EP2014/051406 do provide a significant contribution to the art with the concept of unions, the traffic information and guidance system according to the present invention enables information and guidance services to road users within unions that originate from traffic conditions outside the respective unions. In a sense, the traffic server may intervene and provide qualified advice and information to a union as an added information or as an alternative to observations of members of the union of a specific traffic condition in the union. For example, when avoiding development of severe traffic conditions it may be necessary to update information from a larger geographical area outside the area covered by a union. The union is a superb tool when warning and informing other road users instantly within a limited neighbourhood. However, effects of time dependent evolution of incidents like impact factor magnitude and impact area size etc. is outside the scope of a union since a union probably moves away from a fixed geographical position of an incident, or individual and relative movements of road users away from each other dissolves the union. The present invention is about individual road users and/or unions approaching geographical areas that might have traffic problems causing traffic flow problems for the road users before they come in contact (or union) with closely located road users having information about the specific problem.
On the other hand, a road user listening or using information from a traffic information server usually only need information related to a neighbourhood of his current position at a specific point in time of arrival to the neighbourhood. However, the intended rout that a road user will follow leaving his current position may be unknown to the traffic server (or other members of a union). A traffic server can independently acquire information and traffic measurements online all the time. However, as long as a road user can have independent and random behaviour in the traffic the traffic server may have problems providing specific information and advice that will be relevant for the specific road user. In a sense, the traffic server and a road user are operating individually and without any form of cooperation in the traffic.
According to an aspect of the present invention, solving this and other problems is possible through a system and method thereof, informing and guiding road users approaching junctions. The information can be about traffic flow conditions on roads leading in and out of the junctions. Advices can be how to drive to avoid traffic problems in forward located areas having roads in common with roads leading out of the junctions. Thereby, on the time of arrival in front of the junction, the road user is informed. If a road or street the road user intended to follow when passing the junction have problematic traffic flow conditions, the road user can select another road out of the junction having less traffic problems. Thereby, the junction serves as a decision point for an approaching road user.
Therefore, an improved road traffic information and guidance system would be advantageous, and in particular, a more targeted and/or relevant information and guidance of road users would be advantageous.